Methylation of FOXP3 TSDR Underlies the Impaired Suppressive Function of Tregs from Long-term Belatacept-Treated Kidney Transplant Patients.

Regulatory T cells (Tregs) are considered key players in the prevention of allograft rejection in transplanted patients. Belatacept (BLT) is an effective alternative to calcineurin inhibitors that appears to preserve graft survival and function; however, the impact of this drug in the homeostasis of Tregs in transplanted patients remains controversial. Here, we analyzed the phenotype, function, and the epigenetic status of the Treg-specific demethylated region (TSDR) in FOXP3 of circulating Tregs from long-term kidney transplant patients under BLT or Cyclosporine A treatment. We found a significant reduction in the proportion of CD4+CD25hiCD127lo/-FOXP3+ T cells in all patients compared to healthy individual (controls). Interestingly, only BLT-treated patients displayed an enrichment of the CD45RA+ "naïve" Tregs, while the expression of Helios, a marker used to identify stable FOXP3+ thymic Tregs remained unaffected. Functional analysis demonstrated that Tregs from transplanted patients displayed a significant reduction in their suppressive capacity compared to Tregs from controls, which is associated with decreased levels of FOXP3 and CD25. Analysis of the methylation status of the FOXP3 gene showed that BLT treatment results in methylation of CpG islands within the TSDR, which could be associated with the impaired Treg suppression function. Our data indicate that analysis of circulating Tregs cannot be used as a marker for assessing tolerance toward the allograft in long-term kidney transplant patients. Trial registration number IM103008.

Pretransplant angiotensin II type 1-receptor antibodies are a risk factor for earlier detection of de novo HLA donor-specific antibodies.

BACKGROUND: Angiotensin II type 1 receptor antibodies (AT1Rabs) have been associated with significantly reduced graft survival. Earlier graft loss has been observed in patients who had pretransplant AT1Rabs and posttransplant donor-specific antibodies (DSA). METHODS: The main goal of this retrospective cohort study was to examine the association between AT1Rabs and the time period to detection of de novo human leukocyte antigen (HLA-DSA) posttransplantation in living donor kidney transplant recipients (KTR). The analysis included 141 KTRs. Pretransplant frozen serum samples were tested for AT1Rabs by ELISA and HLA-DSA by SAB (Luminex) at both the pre- and post-KT time points. RESULTS: The median AT1Rab level was 9.13 U (interquartile range 5.22-14.33). After a mean follow-up period of 3.55 years, 48 patients were found to harbour de novo HLA-DSAs. The presence of AT1Rabs [hazard ratio (HR) 1.009, 95% confidence interval (CI) 1.002-1.01, P = 0.010], male-to-male transplantation (HR 2.57, 95% CI 1.42-4.67, P = 0.002) and antecedent borderline changes or acute cellular rejection (ACR) (HR 2.47, 95% CI 1.29-4.75, P = 0.006) were significantly associated with de novo DSA detection. A dose-dependent association between AT1Rab levels (<10 U, 10.1-16.9 U, 17-29.9 U and >30 U) and de novo DSA detection was observed (log-rank P = 0.0031). After multivariate analysis of AT1Rab levels (continuous variable), AT1Rabs >30 U, male-to-male transplantation, donor age, higher class I percentage of Panel Reactive Antibody and antecedent borderline changes or ACR remained as independent significant risk factors for the detection of de novo DSAs. CONCLUSIONS: The findings suggest that higher levels of pretransplant circulating antibodies against AT1R (>30 U) in kidney graft recipients constitute an independent risk factor for earlier de novo HLA-DSA detection during the posttransplant period.

Pre-transplant angiotensin II type 1receptor antibodies: a risk factor for decreased kidney graft function in the early post-transplant period?

Angiotensin II type 1 receptor antibodies (AT1Rab) are associated to a significantly lower graft survival and a higher risk of acute rejection after kidney transplantation. This study aimed to evaluate graft function and BPAR during the 1st year post-transplant (PT) in adult kidney transplant recipients (KTR), between 03/2009 and 08/2012. Pre-KT sera were screened for AT1Rab (ELISA) and HLA-DSA (Luminex). Three groups were analyzed: AT1Rab only (n = 13); HLA-DSA only (n = 8); and no AT1Rab or HLA-DSA (n = 90). No differences were observed in clinical characteristics across groups. A higher percentage of BPAR was observed in the AT1Rab positive group, but this difference was not significant. KTR with AT1Rab had a lower mean eGFR (20 mL/min/1.73m2) when compared to KTR with no Abs at 12 months. The significant difference in eGFR was observed since the 1st month PT. Multivariate analysis showed 4 factors independently and significantly associated with eGFR at 12mos PT: BPAR (-18.7 95%, CI -28.2 to -9.26, p<0.001), AT1Rab (-10.51, CI -20.9 to -0.095, p = 0.048), donor age (-0.42, CI -0.75 to -0.103 p = 0.010), and recipient age (-0.36, CI -0.67 to -0.048, p = 0.024). In this study AT1Rab in pre-transplant sera from KTR, was an independent and significant risk factor contributing to a lower eGFR 12 months. PT. This finding deserves to be confirmed in a larger KTR population.

[Incidence of acute rejection in patients with renal graft dysfunction]. / [Incidencia de rechazo agudo en pacientes con disfunción del injerto renal].

INTRODUCTION: Acute rejection has been identified as the main cause of renal graft dysfunction during the first year after transplantation; it is associated with chronic structural and functional damage, which causes loss of graft and decrease in patient survival. MATERIAL AND METHODS: We performed a retrospective and descriptive research consisting in a review of the final reports of biopsies performed due to renal graft dysfunction during the postransplant period. Patients included were transplanted at the Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán (INCMNSZ) from January 2007 to December 2011. RESULTS: A total number of 223 patients underwent renal transplantation during the period considered for this study purpose, 222 biopsies were performed due to renal graft dysfunction in 118 patients (52.9%). 74.5% of patients developed graft dysfunction in the first year after transplantation. The main histopathological findings reported were immunologic events in both living donor (LDRTR) and deceased donor renal transplant recipients (DDRTR), borderline changes were the most common diagnosis. The median time to detect immune events as cause of dysfunction was shorter for DDRTR and they tend to occur in the first 4 months after transplantation. CONCLUSION: We observed an incidence of 11.8% for acute rejection in the first year after transplantation for LDRTR and 17.4% for DDRTR. Further studies are needed to determine the causes of immunological events and their implications in the evolution of renal graft and patient's survival.

Pre-transplant angiotensin II type 1 receptor antibodies: A risk factor for decreased kidney graft function in the early post-transplant period?

Angiotensin II type 1 receptor antibodies (AT,Rab) are associated with a significantly lower graft survival and a higher risk of acute rejection after kidney transplantation. This study aimed to evaluate graft function and biopsy proven acute rejection (BPAR) during the first year post-transplant in adult renal transplant recipients (RTR), between 03/2009 and 08/2012. Pre-transplant sera were screened for AT1Rab (via enzyme linked immunosorbent assay) and donor specific anti-human leukocyte antigen antibodies (HLA-DSA, via Luminex). Three groups were analyzed: AT1Rab only (n=13); HLA-DSA only (n=8); and no AT1Rab or HLA-DSA (n=90). No differences were observed in clinical characteristics across groups. A higher percentage of BPAR was observed in the AT1Rab positive group, but this difference was not significant. RTR with AT1Rab had a lower median estimated glomerular filtration rate (eGFR=20 ml/min/1.73m2) when compared to RTR with no antibodies at 12 months. A significant difference in eGFR was observed since the first month post-transplant. Multivariate analysis showed four factors independently and significantly associated with eGFR at 12 months post-transplant: BPAR (beta -18.7, 95% CI -28.2 to -9.26, p<0.001), AT,Rab (beta -10.51, 95% CI -20.9 to -0.095 p=0.048), donor age (beta -0.42, 95% CI -0.75 to -0.103, p=0.010), and recipient age (3 -0.36, 95% CI -0.67 to -0.048, p= 0.024). In this study, AT1Rab in pre-transplant sera from RTR was an independent and significant risk factor contributing to a lower eGFR at 12 months posttransplant. This finding deserves to be confirmed in a larger RTR population.

Pre-nephrectomy angiotensin II type 1 receptor antibodies in living kidney donors: A concern?

Angiotensin II type 1 receptor (AT1R) autoantibodies (AT1Rab) have been associated with pre-eclampsia and malignant hypertension. Overactivity of the angiotensin-II/AT1R complex has also been implicated in cardiac, renal, and vascular remodeling, leading to mortality and morbidity from cardiovascular disease. Pre-donation prevalence and possible post-donation effects of AT1Rab in living kidney donors (LKD) are unknown. In this study, sera obtained the day before nephrectomy and kept frozen at -70 degrees C from 113 strictly normotensive and non-obese LKD were tested for AT1Rab by OneLambda detection assay. AT1Rab titers >or=17 international units were considered positive. Pre-donation renal function [estimated glomerular filtration rate (eGFR)] and blood pressure at 1 and 12 months post-donation were recorded in every patient. Ten of 113 (8.8%) LKD yielded a positive AT1Rab result. History of sensitization events was similar in both groups. There was no difference in renal function between LKD with positive and negative AT1Rab results, 1 (mean eGFR 73.8 versus 72.4 mL/min/1.73m2) and 12 months post-donation (mean eGFR 74.1 versus 74.5 mL/min/1.73m2). During follow-up, none of the LKD developed hypertension (defined as blood pressure >130/85), nor did they require antihypertensive drugs. AT1Rab are apparently indolent in healthy adults after short-term follow-up. Longer observation of all LKD will be necessary to draw final conclusions.